Your grandparents and their friends may have simply been lucky. You also have to be careful of survivorship bias. Yes, a high infant mortality rate skews the f

Your grandparents and their friends may have simply been lucky. You also have to be careful of survivorship bias. Yes, a high infant mortality rate skews the figures. Still, I'd be willing to bet that the average 40 year old in 1929 had a life expectancy at least 10 years less than the average 40 year old in 2017. Edit: Table 21 in this report is informative: https://www.cdc.gov/nchs/data/nvsr/nvsr64/nvsr64_11.pdf https://www.cdc.gov/nchs/data/nvsr/nvsr64/nvsr64_11.pdf Expected years remaining for a 40 year old in 1929-31 was 29.67. In 2011 it was 40.58.